When casting a metal part having cavities, openings, surfaces or paths, it is common in the foundry industry to use solidified sand-shapes to acquire the desired interior and/or exterior geometry. Such sand-shapes can be used singularly or in combination in a casting operation. Specifically, the cast part is formed by pouring molten metal into or around the sand-shape. Upon completion of casting the metal part, the sand-shape(s) is(are) broken down, shaken-out, de-solidified or otherwise removed from the metal part. Accordingly, the casting process often begins with the forming of one or more sand-shapes corresponding to the desired geometry of the to-be-cast metal part.
A sand-shape (e.g., a sand core or a sand mold) is typically formed in a core box comprising a cope and drag, which define a cavity of the desired geometry therebetween. The core box is designed for receipt of a blow tube assembly that conveys prepared sand (e.g., conditioned with chemicals or resins so that it remains flowable) from a sand magazine into the cavity. The core box also can have vent passages in its cope and/or drag to allow air to escape from the cavity as it is filled with sand.
After the sand is blown into the cavity, the blow tube assembly is withdrawn from the core box. The exiting of the blow tube often tends to create a slight pile of sand in the cope just above the cavity from excess sand falling out of the blow tube due to the angle of repose. To avoid imperfections on the cope side of the finished sand-shape, the industry norm is to pat or tamp these little piles of sand with tamper pins prior to the catalyst-solidifying steps.
After removal of the blow tube assembly (which is fastened to the sand magazine via the blow plate), a gassing manifold is subsequently positioned over the core box to form a sealed chamber, which covers the blow tube opening and the cope passages. Tamping steps are usually performed at this point with pins, which hang from a plate inside the manifold chamber. Cylinders or springs typically actuate the tamper plate movement. A solidifying catalyst then is introduced through inlet ports in the manifold, travels through the blow tube cope opening and core vent passages, and then exits through the drag vent passages. After an appropriate curing time, the cavity is purged with air to remove any residual catalyst vapors. The core box may then be separated for the ejection and removal of the cured sand-shape.
It may be noted that between the sand-blowing steps and the catalyst-introducing steps, a conventional sand-forming apparatus necessitates the withdrawal of the blow tube assembly and transfer of the manifold. It may also be noted that the current trend in the industry is to encompass all of the sand-forming components (e.g., the sand supply magazine, the cope box, the manifold etc.) in an enclosure, thereby providing a segregated area for exhausting catalyst vapors. While such an enclosure may shield the outside environment from the undesirable vapors, it does not prevent residual catalyst vapors from unintentionally curing the remaining sand in the blow tube assembly or the sand magazine.
In the past, sand-forming methods have been proposed and/or attempted that would enable the sand-blowing steps and catalyst-introducing steps to be performed with the same equipment. These proposed/attempted methods experienced very limited (if any) success and were not without significant drawbacks. For example, the modification of the sand blow plate to allow for catalyst passages to be introduced along side each of the blow tube had been proposed. However, this modification did not provide any way of preventing contamination and hardening of sand contained in the blow tube. The replacement of conventional core boxes with ones having complicated drill patterns, bladder sealing, and indirect blowing paths also have been proposed. However, these proposals require an industry-wide scrap of literally all existing core boxes (or at least the cope halves) and, moreover, do not provide uniform sand distribution from the end of the blow tube. Special blow tubes also have been attempted, with lateral blowing and gassing exits to feed peripheral areas of the cores.
All in all, these proposed and attempted solutions fail to provide uniform sand distribution (i.e., they fail to fill below the tube adequately) to fill the core box in a conventional manner, fail to make use of existing common and accepted core box designs, fail to accommodate ventilation through the top side of the cope, and/or fail to address the need for tamping prior to catalyst-introducing steps. Moreover, past proposed and attempted methods have failed to provide these features while also providing for controlled containment of the catalyst.